Actuating arrangements



Oct. 24, 1967 P. B. KAHN ETAL ACTUATING ARRANGEMENTS Fil ed April 5, 1965 United States Patent 3,348,454 ACTUATTYG ARRANGEMENTS Peter B. Kahn, Catistield, Fareham, and Thomas Alfred Oldfield, Warsash, England, assignors to Plessey-UK Limited, Essex, England, a British company Filed Apr. 5, 1965, Ser. No. 445,619 2 Saints. (Cl. 9144) ABSTRACT OF THE DISCLQSURE A double-acting fluid-pressure actuated thrust-reverse ram co-operates with a locking member which is springurged to a position in which it prevents movement of the ram from one of its two end positions, and the admission of fluid pressure, to, and its release from, the two sides of the ram piston is controlled by a shuttle-type slide valve connected for common movement with a servo-piston which is controlled by a pilot valve and is lost-motion coupled to the locking member so that, while allowing free movement of the servo piston when the locking member is in its unlocked position, it will force the locking member to its unlocked position when the piston is moved to the position in which the valve admits fluid to the ram to move it from its lockable position, the length of the lands of the shuttle valve being suflicient to prevent admission of fluid pressure to the ram cylinder for movement from the lockable position when the shuttle valve is moved to produce such movement until the servo-piston and valve have moved sufficiently to render the locking member inoperative.

Disclosure This invention relates to an actuator system and is more particularly concerned with a hydraulic or pneumatic control system for the operation of a ram or the like.

A hydraulic or pneumatic ram is frequently arranged to operate between a first position in which the ram is extended outwardly from the ram cylinder and a second position in which the ram is retracted into the ram cylinder. Control arrangements for actuating the ram are usually provided with mechanical locking or catch devices which are adapted to lock the ram when in its extended position. If desired the ram could be lockable when in other positions. Conveniently such mechanical locking devices utilise a catch which is arranged and adapted to lock with the ram when the latter has moved to its extended position.

A selectively movable control valve is usually provided for guiding the air or hydraulic fluid to the selected side of the piston so as to actuate the ram in the required direction. in a known arrangement for controlling the operation of a catch device for locking the ram in its extended position the air pressure which is used to operate the ram itself is also used to move the catch device into or out of its locking position. This apparatus has hitherto suffered from the difliculty that the pneumatic pressure or hydraulic pressure applied to the catch device, particularly in the catch releasing sense, is simultaneously applied to the ram itself so that there is a tendency for the ram to move before the catch device has been released. This overlap between catch release and ram movement results in unnecessary wear and inefliciency of operation.

Broadly, in accordance with the present invention there is provided an actuator system including a main ram locking means for locking the main ram against movement from a predetermined position or positions, the locking means being resiliently loaded so that it is automatically moved on to its locking position whenever the main ram is in said position or in one of said positions, a control valve for selectively controlling the application 3,343,454 Patented Get. 24, 1967 of pressurised working fluid to move the main ram, and control means for moving the locking means to its released position, said control valve being so operatively inter-related with the control means that the latter can fully release the locking means before the control valve can be so operated as to cause the main ram to move.

For a better understanding of the invention and to show how the same may be carried into efiect reference will now be made to the accompanying drawing which is a schematic representation of an actuator system incorporating the features of the present invention. The actuator system basically includes a main ram 1, which is connected at one end to a piston 2 reciprocable within a cylinder 3. The ram 1 is connected via a pivoted link 4 to operate the unit (not shown) which is to be positionally controlled by the ram 1. The link 4 is connected at 4A intermediate of the ends thereof to the unit the other end of the link 4 being connected to a baulk rod 5. The position of the ram 1 within the cylinder is controlled by air which is applied to one or the other sides 6 or 7 of the piston 2. This air is derivable from a high-pressure air inlet duct 8 via a control or sequencing valve unit 9. The unit 9 includes a cylinder 10 within which a shuttle-type valve element 11 is reciprocable. Two relatively wide lands 13 and 14 of the shuttle element 11 co-operate with a series of ports provided in the wall of the cylinder 10, which by the lands 13 and 14 is divided into'three aligned separate chambers 15, 16 and 17, the outer two of which are of oppositely variable sizes and are exhausted to atmosphere via ports 23 and 24 respectively.

The high-pressure air inlet duct 8 is connected with the central chamber 16 via a port 18 in the cylinder 10. That end of the ram cylinder 3 which faces the side 7 of the piston 2 is connected via a duct 19 with one service port 20 and the other end of the cylinder 3 communicates via a duct 1 with a second service port 22 of the cylinder 10. In the arrangement as so far described it will be appreciated that the high-pressure inlet air is fed to one or the other sides of the piston 2 according to the position of the valve element 11 Within the cylinder 10. When the piston valve 11 is in the position shown, high-pressure air is applied to the side 7 of the piston 2 and the side 6 of the piston 2 is exhausted to atmosphere via the duct 21 the port 22 the chamber 15 and the port 23. When the valve element 11 is moved into its alternative position at the other end of the cylinder 10, high-pressure air is instead admitted via the port 22 and the duct 21 to act upon the other side 6 of the piston 2 whilst the side 7 of the piston 2 is vented to atmosphere via the duct 19 the port 20 the chamber 17 and the port 24. It Will be understood that with the valve in this alternative position, the land 14 is located to the left-hand side of the port 20.

The valve element 11 is rigidly coupled via a piston rod 25 with a servo-piston 26 which is reciprocable within a cylinder 27 and is secured to an extension 28 of the piston rod 25, which serves to operate an automatic locking unit 29 which is associated with the baulk rod 5. This locking unit includes a cranked lever 30 which is pivotally mounted on a fixed pin 31 which extends through a longitudinal guide slot 32 of the baulk rod 5. One arm of the lever 30 carries a stop 33 which in the illustrated position faces the free end of the baulk rod 5, thus locking, by means of the latter, the ram 1 against movement from its illustrated extended position. The other arm of the lever 39 has a longitudinal slot through which extends a floating pin 34 which also engages a longitudinal slot 35 in the piston rod 23 to establish a lost-motion connection between the piston rod extension 28 and the crank lever 30, which when the valve element 11 is in the illustrated position, allows the locking lever free movement between the unlocked and the illustrated locked positions, while ensuring that movement of the valve element 11 to its opposite end position moves the locking lever 30 to an inoperative position before fluid is admitted to the ram cylinder 3 for reversing the position of the ram. A spring 37 resiliently loads the lever 30 towards the illustrated locked position illustrated in the drawing.

To displace the piston 26 relative to the cylinder 27 high-pressure air is admitted to either side 38 or 39 of the piston from the high-pressure air input duct 8 via a servoselector valve 9 under the control of a pilot unit 40.

The said first pilot unit includes a shuttle-type pilot valve element 41 slidable Within a cylinder 42, which by the two lands 43 and 44 of the element 41 is divided into three chambers 45, 46 and 47. High-pressure air is admitted to the central chamber 46 from the inlet duct 8 via a duct 48 terminating in a port 49 in the wall of the cylinder 42. Two service ports 51 and 52 spaced similarly to the lands 43 and 44 of the valve element 11, are provided in the cylinder 42 and respectively connected via ducts 50 and 52 to the cylinder 27 at the two sides 38, 39 of the piston 26, and the two outer chambers 45 and 47 of the valve cylinder 42 are vented to atmosphere via ducts 54, 55. The above described arrangement operates as follows: It will be presumed that the settings of the various rams and valves are as illustrated in the drawing. In this position the high-pressure air supply is fed via the duct 48, the port 49, the chamber 46, the port 51 and the duct 50 to act upon the side 38 of the piston 26. The application of the pressure on this side tends to move the piston 26 towards the left-hand end of the cylinder 27. The side 39 of the piston 26 is vented to atmosphere via the duct 52, the port 53, the chamber 47 and the port 55. The piston 26 thus moves to the left-hand end of the cylinder 27 and in so doing it pivots the locking lever 30 about its pivot 31 against the loading of the spring 37 so as to move the lock member 33 out of the path of the baulk rod 32.

The movement of the piston 26 to the left-hand end of the cylinder 27 moves the servo-selector valve 11 towards the left-hand end of the cylinder 10. When the piston is moved into this direction the high pressure air flow through the duct 8 is led via the port 13, the chamber 15, the port 22 and the duct 21 to apply pressure against the side 6 of the ram piston 2. At the same time the side 7 of the ram piston 2 is vented to atmosphere via the duct 19, the port 20, the chamber 17 and the port 24. Since the lands 13 and 14 of the piston valve 11 are relatively wide the ram rod is able to complete the unlocking of the baulk rod before the high pressure air flow is actually transferred from the inlet 8 to the port 22. The pressure acting on the side 6 of the piston 2 moves the piston towards the right-end of the cylinder and in so doing pulls the ram 1 inwards. This movement of the ram 1 pivots the lever 4 in a clockwise direction thereby to actuate the units which have to be operated by the ram. At the same time the movement of the lever 4 moves the baulk rod 5 towards the left to its extended position, the rod moving relative to the pivot 31 by means of the slot 32. When the baulk rod 5 is in the extended position the locking lever i held in the unlocked position, against the spring loading, by the rod 5 in that stop 33 is positioned above and rests on rod 5. When it is required to move the ram piston 1 in the reverse direction the piston valve 41 is moved towards the right-hand end of the cylinder 40. This movement vents the side 38 of the piston 26 to atmosphere via the duct 50, the port 51, the chamber 45 and the duct 54. The high-pressure air supply is then fed via the duct 48, the port 49, the chamber 46, the port 53, the duct 52 to act upon the side 39 of the piston 26, to move the latter back to the position shown in the drawing. During the movement of the ram piston 26 the slot is 70 moved relative to the pin 34 and member 29 is held stationary by the engagement of stop 33 above rod 5 until rod 5 retracts .sufficiently to clear stop 33.

As previously explained the piston 26 substantially completes its stroke before the control piston 11 has been moved to such an extent that the direction of the high pressure air on the ram piston 2 is reversed. On reversal of the pressure, i.e. the side 7 is subjected to the high pressure air and the side 6 is vented to atmosphere, the ram 1 is returned to the position shown in the drawing.

As soon as the ram 1 substantially reaches its extended position, the baulk rod 5 is returned to its retracted position so that the spring loading on the lever 30 is able automatically to return the lever to the locking position shown in the drawing. It will be appreciated that the pin 34 is able to move lengthwise of the slot 35 during the movement of the lever 36.

if desired the system could be hydraulically actuated, provided the vents to atmosphere were returned to the low pressure side of the system.

The actuator system described above is particularly suitable for use in thrust reversing installation for an aircraft engine. In this application the ram 1 is locked in such position that the thrust reverse doors or the like are open. In practice the doors or the like would be pivoted by the pivotal movement of the link 4.

What we claim is:

1. A control system for a thrust reverser having a double-acting ram cylinder, a ram piston, movable along this cylinder, and mechanical locking means movable when the rampiston is at one end of its stroke between a locking position in which said locking member prevents movement of the ram piston from said one end position and an inoperative position in which said locking member permits such movement of the ram piston, the system comprising means for resiliently urging the locking member to said locking position, a control valve having a shuttle-type valve element controlling the admission of fluid pressure to and the release of pressure from the ram cylinder at the two sides of said piston respectively, and lost-motion coupling means connecting said valve element with the locking member for forcing the locking member to its inoperative position against said resilient means when said valve element is moved to one end position while permitting movement of the valve element to its other end position irrespective of the position of said locking member, said shuttle-type valve element having lands of such length as to permit sufiicient movement of the valve element from said other end position towards said one end position to render the locking element inoperative before admitting fluid pressure to the ram cylinder for movement of the ram piston from said one end position to the opposite end of its stroke.

2. A thrust reverser control system as claimed in claim 1, including a servo-cylinder containing a servo-piston connected to said valve element for common movement therewith in both directions, and a pilot valve controlling service connections to the servo-cylinder at the two sides respectively of the servo-piston for causing fluid pressure to move the servo-piston in one or the other direction according to the piston of the pilot valve.

References Cited UNITED STATES PATENTS 857,232 6/1907 Forman 9l-4l 2,243,626 5/1941 Gregg et al. 9144 2,838,027 8/1958 Branick 9l41 3,086,360 4/1963 Gavin 91-41 3,141,382 7/1964 Oldfield et al. 9l-44 3,227,048 1/1966 Criflield et al. 9l-4l 3,270,621 9/1966 De Ridder 9l44 MARTIN P. SCHVVADRON, Primary Examiner.

B. L. ADAMS, Assistant Examiner. 

1. A CONTROL SYSTEM FOR A THRUST REVERSER HAVING A DOUBLE-ACTING RAM CYLINDER A RAM PISTON, MOVABLE ALONG THIS CYLINDER, A MECHANICAL LOCKING MEANS MOVABLE WHEN THE RAM PISTON IS AT ONE END OF ITS STROKE BETWEEN A LOCKING POSITION IN WHICH SAID LOCKING MEMBER PREVENTS MOVEMENTS OF THE RAM PISTON FROM SAID ONE END POSITION AND AN INOPERATIVE POSITION IN WHICH SAID LOCKING MEMBER PERMITS SUCH MOVEMENT OF THE RAM PISTON, THE SYSTEM COMPRISING MEANS FOR RESILIENTLYL URGING THE LOCKING MEMBER TO SAID LOCKING POSITION, A CONTROL VALVE HAVING A SHUTTLE-TYPE VALVE ELEMENT CONTROLLING THE ADMISSION OF FLUID PRESSURE TWO SIDES OF SAID PISTON RESPECTIVELY, AND LOST-MOTION TWO SIDES OF SAID PISTON RESPECTIVELY, AND LOST-MOTION COUPLING MEANS CONNECTING SAID VALVE ELEMENT WITH THE LOCKING MEMBER FOR FORCING THE LOCKING MEMBER TO ITS INOPERATIVE POSITION AGAINST SAID RESILIENT MEANS WHEN SAID VALVE ELEMENT IS MOVED TO ONE END POSITION WHILE PERMITTING MOVEMENT OF THE VALVE ELEMENT TO ITS OTHER END POSITION IRRESPECTIVE OF THE POSITION OF SAID LOCKING MEMBER, SAID SHUTTLE-TYPE VALVE ELEMENT HAVING LANDS OF SUCH LENGTH AS TO PERMIT SUFFICIENT MOVEMENT OF THE VALVE ELEMENT FROM SAID OTHER END POSITION TOWARDS SAID ONE END POSI- 